The instrument requested is the Affymetrix GeneChip Scanner 3000 Instrument System (GCS 3000). In addition, an extra Fluidics 450 Station is requested to be utilized in constructing a single instrument system. The scanner incorporates advanced design improvements, which improve automation and improve throughput efficiency. In addition, the new scanner provides more accurate gridding and more consistent scanner-to-scanner biological performance than the previous model (GCS 2500). These advances in design are quite important in improving data integrity and data sharing between researchers, as is proposed by the current major user group. In addition, the GCS 3000 is designed to accommodate future advances in GeneChip technology. This Instrumentation System of a single GCS 3000 provides all the necessary components to perform Affymetrix array experiments. The major components include one each of the following components: Computer Workstation, Hybridization Oven, GeneChip Scanner 3000, Fluidics Station 450. We seek to complete the instrument System by also purchasing a second Fluidics Station to be used in parallel in the system. The newest Fluidics Station 450 design has modular components for easier maintenance and more precise washing and staining. In addition, our experience to date indicates that the array staining and washing steps represent the major "bottleneck" of system capacity. There are two major reasons for the equipment justification: First, the currently available equipment (the older Affymetrix GCS 2500 and supplementary Fluidics Station 400) is maximally utilized by the existing Gene Expression Facility. This fact is demonstrated below in the documentation of the current usage. Second, the major group of users assembled on the UCHSC campus relate to the NHLBI Shared Microarray Facility Consortium awarded to Dr. Geraci. This group represents the major user group for the requested equipment, and cannot be accommodated by the currently used system, due to the use being at full capacity. The accessory to be utilized in the current proposal is an extra fluidics station. This new system, as proposed, would put the capacity of continuous fluidics at 8 arrays during simultaneous usage. Dr. Geraci was recently awarded from the NHLBI a shared microarray facility grant entitled " Expression analysis to study disease pathogenesis" (1) RO1HL 72340-01. This grant was expressly designed for the designated major user group to perform, with high throughput, microarray experiments in their ongoing research efforts.